ARPA

Question 1

Which of the following contributes to assessment of risk of collision?

Answer 1

• Relative motion line (CPA/TCPA)
• Aspect
• Amount of error in the calculations

Question 2

What controls would you adjust if known targets were not being detected by RADAR?

Answer 2

• Gain
• Suppressions
• Range Scale

Question 3

A RADAR contact will remain stationary on a relative motion radar display only when it is…

Answer 3

On the same course and speed as your vessel

Question 4

The CPA of a contact on a relative motion RADAR may be determined:

Answer 4

After the contact has been marked at least twice over a period of at least a minute.

Question 5

A RADAR display in which the orientation of the display is fixed so that North is always at the top of the screen is called a/an

Answer 5

Stabilized display

Question 6

What inputs are required to maintain a North-up, True Motion display

Answer 6

Gyro course and Log speed

Question 7

In addition to ARPA info, an ARPA user should take into account:

Answer 7

• The limitations of that info
• ROR
• The circumstances of the situation including external considerations

Question 8

In restricted visibility what should you avoid when altering course for a vessel forward of your beam that you cannot see visually?

Answer 8

Altering course to port except in overtaking situations

Question 9

When two ARPA equipped ships collide, which of the following is typically true?

Answer 9

Both vessels are likely to be found at fault.

Question 10

When using ARPA, what should you consider in order to evaluate the info displayed?

Answer 10

Navigational constraints may require a target vessel to change course

Question 11

Which of the following info is least dependent of ARPA processing?

Answer 11

EBL/VRM data

Question 12

According to IMO, log and speed indicators providing inputs to ARPA equipment should be capable of providing:

Answer 12

The ship’s speed through the water

Question 13

What is the min. number of targets that an IMO approved ARPA must track simultaneously?

Answer 13

20 targets

Question 14

What is the lowest range scale that IMO requires ARPA facilities to be available on?

Answer 14

3 miles

Question 15

According to IMO standards, the ARPA data display:

Answer 15

Should be visible to more than one observer in conditions of light normally experienced on the bridge by day or night.

Question 16

Regarding the IMO requirement for past positions

Answer 16

All ARPAs can display both true and relative past positions

Question 17

IMO requires ARPA to operate in relative motion with:

Answer 17

Either north-up or head-up or course-up display

Question 18

According to IMO performance standards, what should an ARPA do to improve the standard of collision avoidance at sea?

Answer 18

ARPA should reduce the workload of observers by automatically providing information.

Question 19

The ARPA facilities should be available on at least the following range scales:

Answer 19

3 or 4 miles and 12 or 16 miles

Question 20

Two conditions needed for +/- steady state tracking

Answer 20

1. Ownship maintains course & speed
2. Target maintains course & speed

Question 21

Which of the following is NOT a required operational warning on ARPA’s

Answer 21

Automatically Acquired Target

Question 22

The NavLines displayed on an ARPA

Answer 22

Will drift when ARPA is sea-stabilized.

Question 23

Gradual alterations of course will help the ARPA process data faster and provide more accurate info?
True or False

Answer 23

False

Question 24

When observing a target’s past positions in TM what informatino can be quickly “gleaned”?

Answer 24

Target has changed course

Question 25

Watchstanders can measure error in the ARPA presented information by using:

Answer 25

A plotting sheet or grease pencil plot on a reflection plotter.

Question 26

You observe a target visually dead but is displayed on your RADAR at 5 degrees to STBD of the heading flash. How would you correct this?

Answer 26

Check the scanner for antenna misalignment.

Question 27

When an ARPA-tracked target maneuvers:

Answer 27

First indication of a maneuver will probably be seen on a persistence or afterglow feature if your ARPA has one

Question 28

Regarding ARPA errors, which of the following is true?

Answer 28

Relying on ARPA information can be dangerous

Question 29

The vector displayed after 3 minutes of steady state tracking:

Answer 29

Represents the targets probable pas projected into the future

Question 30

When operating a RADAR in fog, it is possible to have a limited effective range? True or False

Answer 30

True

Question 31

Which general statement concerning RADAR is **NOT** true?

Answer 31

The ability of RADAR to detect objects is unaffected by weather conditions

Question 32

When operating a RADAR in fog RADAR ranges are less accurate? True or False

Answer 32

False

Question 33

You will get an alarm if target swap has occured. True or False

Answer 33

False

Question 33

If CPA/TCPA alarm is continually going off what should you do?

Answer 33

Adjust the limits to reflect the conditions

Question 34

What input to an ARPA is needed for sea stabilized info?

Answer 34

RADAR input, gyro heading, and STW

Question 35

What do ground stabilized true vectors intended to represent?

Answer 35

The recent track of a target's motion over the ground projected into the future

Question 36

When using navlines for nav, which stabilization method should be used?

Answer 36

Ground

Question 37

When can Trial Manuever mode display inaccurate information?

Answer 37

When the ARPA (vectors) are ground stabilized.

Question 38

When using a course-up stabilized display

Answer 38

The heading flasher does not move when you change course

Question 39

Which of the following statements is TRUE regarding AIS?

Answer 39

AIS provides the other vessel's identity, dimensions and navigational status regardless of visibility

Question 40

Which of the following is true of the history display of past positions on an ARPA?

Answer 40

In the true presentation, it provides a quick visual check to determine if a vessel has changed course

Question 41

If your speed input is incorrect, what effect would it have on your ARPA data?

Answer 41

True vectors would be incorrect

Question 42

Cases in which your ARPA will alarm.

Answer 42

- Target initially detected in guard zone - Target tracked who violates CPA/TCPA limits - Lost target - Tracked target who violates BCT/BCR - ARPA failure - Input loss

Question 43

Your ARPA has two guard "trip wire" ring alarms. What is the purpose of the inner guard ring?

Answer 43

Warn of small targets that are initially detected closer than the outer guard ring

Question 44

When ARPA's are used in sea stabilized mode with true tracks, data relating to own ship's motion is fed to the ARPA from the ___.

Answer 44

Speed log and gyro

Question 45

When your ship is in a cross current, the NavLines on your ARPA screen will remain staionary, or near stationary, when you operate in

Answer 45

Ground stabilized mode

Question 46

Which warning is required by the IMO performance standards?

Answer 46

A warning any time a target closes to a designated range or transits a zone, chosen by the observer.

Question 47

Provided a target is not subject to target swap, the ARPA should continue to track an acquired target which is clearly distinguishable on the display for___

Answer 47

5/10 consecutive scans

Question 48

Which of the following is NOT a commonly used term for ARPA's target persistence of afterglow?

Answer 48

History dots

Question 49

Conditions that would cause a fixed target to appear to have a true speed of more than zero.

Answer 49

- Centroid shift - Current - Incorrect speed input on ARPA - Target swap